1. Field of the Invention
The present invention relates to a data communication apparatus, method and system, and to programs for a data communication process stored in a computer readable storage medium. More particularly, the invention relates to data communication techniques using communication control buses capable of dealing with mixed control and data signals.
2. Related Background Art
A need for using an apparatus dealing with still or moving images, such as AV (audio visual) apparatuses, as a peripheral apparatus of a personal computer has recently become strong. The AV apparatuses include a digital video tape recorder (D-VTR), a digital video tape recorder with a built-in camera (D-CAM), a digital camera, and the like. For such needs, a system has been developed which can connect such AV apparatuses to PC and can process and edit in various ways digital signals of still and moving images taken with AV apparatuses. Another system has also been developed in which PC can record still and moving image signals from AV apparatuses in a recording medium such as a hard disk, and can print such images with an image printing apparatus such as a printer.
In order to reduce the amount of still and moving image data to be transferred between apparatuses constituting such a system, the image data is converted into compressed data by using various compression encoding techniques. For example, a JPEG (Joint Photographic Experts Group) method is known for still images, and an MPEG (Moving Picture Experts Group) method is known for moving images. These compression encoding methods are realized by a combination of DCT techniques and variable length coding techniques, while taking into consideration the characteristics and features of image data to be compressed.
FIG. 1 is a block diagram showing the structure of a conventional communication system. In FIG. 1, reference numeral 101 represents a D-CAM (recording/reproducing device), 102 represents a printer, and 103 represents a PC. PC 103 and the printer 102 are interconnected by communication interfaces of SCSI (small computer system interface) specifications. PC 103 and D-CAM 101 are interconnected by dedicated communication interfaces.
In the communication system shown in FIG. 1, for example, the following processes have been executed in printing a still image contained in moving images reproduced with D-CAM 101.
PC 103 temporarily stores moving image data sequentially output from D-CAM 101 in a storage device such as a hard disk. Next, PC 103 reproduces the moving images by using a predetermined application, and selects a desired still image of one frame from the moving images. In this case, a user performs a special effect process for the selected still image, if necessary, and thereafter instructs to print the still image. In response to this instruction, PC 103 supplies the still image data to the printer 102 connected thereto via a communication interface different from that for D-CAM 101. Lastly, the printer 102 prints out the still image. As above, the communication system shown in FIG. 1 prints a still image contained in moving images with the help of PC 102.
With the communication system described above, however, in order to select a desired still image contained in moving images produced with D-CAM 101, the moving image is required to be temporarily stored in the storage device such as a hard disk of PC 103. PC 103 then reproduces moving image data stored in the storage device to select a desired still image.
In the conventional communication system, therefore, a large amount of data such as moving image data is sequentially sent to PC 103 each time in the unit of a predetermined amount of data, so that a load of PC 103 is very large. Depending upon the process performance and condition of PC 103 itself or upon a communication state of each apparatus, PC 103 may become inoperative or adversely affect the communication with other apparatuses. Furthermore, since a desired still image is selected after the moving image data stored in PC 103 is reproduced, it takes a long time to print the still image.
In the communication system shown in FIG. 1, in order to reduce the amount of moving image data to be transmitted from D-CAM 101 to PC 103, the moving image data is compressed at D-CAM 101 by a predetermined compression encoding scheme, and the compressed data is transmitted to PC 103.
However, even if D-CAM 101 transmits compressed moving image data, a desired still image cannot be selected unless PC 103 itself can expand and decode the compressed moving image data.
In the communication system shown in FIG. 1, if moving image data irrelevant to the compression coding scheme used by PC 103 is to be transmitted, D-CAM 101 has conventionally transmitted non-compressed moving data itself to PC 103.
However, if PC 103 has an expansion decoding scheme corresponding to the compression encoding scheme of D-CAM 101, a transmission efficiency is lowered unnecessarily and a load on PC 103 is increased.
An object of the present invention is to solve the above-described problems.
Another object of the invention is to provide a data communication apparatus in which an encoding process for information data to be transmitted is performed in accordance with a decoding performance at an object node apparatus, to thereby improve the communication efficiency and reduce a capacity of a memory used for communications.
As a preferred embodiment for such objects, the invention discloses a data communication apparatus which comprises: (a) communication means having a first mode of transmitting information data isochronously with a predetermined communication cycle and a second mode of transmitting information data asynchronously with the predetermined communication cycle; (b) encoding means for encoding the information data by a predetermined encoding method; and (c) control means for controlling the communication means so as to transmit encoded information data when the encoding method corresponds to a decoding method at an object node apparatus and to transmit non-encoded information data when the encoding method does not correspond to the decoding method at the object node apparatus.
As another embodiment, the invention discloses a data communication apparatus which comprises: (a) communication means having a first mode of communication isochronous with a predetermined communication cycle and a second mode of communication asynchronous with the communication cycle; (b) encoding means for encoding image information in accordance with a decoding performance at an object node apparatus, the image information including moving image information and still image information; and (c) control means for controlling the communication means so as to transmit the moving image information by using the first mode and to transmit the still image information by using the second mode.
As another embodiment, the invention discloses a data communication apparatus which comprises: (a) input means for inputting moving image information and still image information; (b) encoding means for encoding the moving image information and the still image information; and (c) transmitting means for transmitting the moving image to a number of unidentified apparatuses and transmitting the still image information to a designated apparatus.
As another embodiment, the invention discloses a data communication apparatus which comprises: (a) input means for inputting information data; (b) encoding means for encoding the information data; and (c) transmitting means for transmitting decode information containing program codes realizing the decoding method corresponding to an encoding method to be used by the encoding means and transmitting the information data encoded by the encoding means.
As another embodiment, the invention discloses a data communication apparatus which comprises: (a) input means for inputting encoded information data and decode information realizing a decoding process for the information data; and (b) decoding means for decoding the encoded information data by using the decode information.
As another embodiment, the invention discloses a data communication apparatus which comprises: (a) encoding means for encoding information data by using a predetermined encoding method; (b) decoding means for decoding information data encoded by the encoding means; and (c) selecting means for selecting an output of either the encoding means or the decoding means in accordance with whether the encoding method corresponds to a decoding method at an object node apparatus.
Another object of the present invention is to provide a data communication method in which an encoding process for information data to be transmitted is performed in accordance with a decoding performance at an object node apparatus, to thereby improve the communication efficiency and reduce a capacity of a memory used for communications.
As a preferred embodiment for such an object, the invention discloses a data communication method which comprises the steps of: (a) encoding information data by a predetermined encoding method; (b) transmitting encoded information data isochronously with a predetermined communication cycle when the encoding method corresponds to a decoding method at an object node apparatus; and (c) transmitting non-encoded information data asynchronously with the communication cycle when the encoding method does not correspond to the decoding method at the object node apparatus.
As another embodiment, the invention discloses a data communication method which comprises the steps of: (a) encoding image information in accordance with a decoding performance at an object node apparatus, the image information including moving image information and still image information; (b) transmitting the moving image information by using a communication scheme isochronous with a predetermined communication cycle; and (c) transmitting the still image by the communication scheme isochronous with the communication cycle or by a communication scheme asynchronous with the communication cycle.
As another embodiment, the invention discloses a data communication method which comprises the steps of: (a) inputting moving image information and still image information; (b) encoding the moving image information and the still image information; and (c) transmitting the moving image to a number of unidentified apparatuses and transmitting the still image information to a designated apparatus.
As another embodiment, the invention discloses a data communication method which comprises the steps of: (a) inputting information data; (b) encoding the information data; and (c) transmitting decode information containing program codes realizing the decoding method corresponding to an encoding method to be used at the encoding step and transmitting the information data encoded at the encoding step.
As another embodiment, the invention discloses a data communication method which comprises the steps of: (a) inputting encoded information data and decode information realizing a decoding process for the information data; and (b) decoding the encoded information data by using the decode information.
As another embodiment, the invention discloses a data communication method which comprises the steps of: (a) encoding information data by using a predetermined encoding scheme; (b) decoding information data encoded at the encoding step; and (c) selecting an output of either the encoded information data or the decoded information data in accordance with whether the encoding scheme corresponds to a decoding scheme at an object node apparatus.
Another object of the present invention is to provide a data communication system in which an encoding process for information data to be transmitted is performed in accordance with a decoding performance at an object node apparatus, to thereby improve the communication efficiency and reduce a capacity of a memory used for communications.
As a preferred embodiment for such an object, the invention discloses a data communication system having a first mode of transmitting information data isochronously with a predetermined communication cycle and a second mode of transmitting information data asynchronously with the predetermined communication cycle, wherein encoded information data is transmitted when a predetermined encoding scheme corresponds to a decoding scheme at an object node apparatus and non-encoded information data is transmitted when the encoding scheme does not correspond to the decoding scheme at the object node apparatus.
As another embodiment, the invention discloses a data communication system having a first mode of communication isochronous with a predetermined communication cycle and a second mode of communication asynchronous with the communication cycle, wherein moving image information encoded in accordance with a decoding performance at an object node apparatus is transmitted by using the first mode and still image information encoded in accordance with the decoding performance at the object node apparatus is transmitted by using the first or second mode.
As another embodiment, the invention discloses a data communication system, comprising: (a) a transmission apparatus for transmitting decode information containing program codes realizing a decoding method corresponding to a predetermined encoding method and transmitting information data encoded by using the encoding method; and (b) a reception apparatus for receiving the decode information and the information data and decoding the information data by using the decode information.
Another object of the present invention is to provide a program for a data communication process stored in a computer readable storage medium, in which an encoding process for information data to be transmitted is performed in accordance with a decoding performance at an object node apparatus, to thereby improve the communication efficiency and reduce a capacity of a memory used for communications.
As a preferred embodiment for such an object, the invention discloses a program for a data communication process stored in a computer readable storage medium, comprising the steps of: (a) encoding information data by a predetermined encoding method; (b) transmitting encoded information data isochronously with a predetermined communication cycle when the encoding method corresponds to a decoding method at an object node apparatus; and (c) transmitting non-encoded information data asynchronously with the communication cycle when the encoding method does not correspond to the decoding method at the object node apparatus.
As another embodiment, the invention discloses a program for a data communication process stored in a computer readable storage medium, comprising the steps of: (a) encoding image information in accordance with a decoding performance at an object node apparatus, the image information including moving image information and still image information; (b) transmitting the moving image information by using a communication scheme isochronous with a predetermined communication cycle; and (c) transmitting the still image by the communication scheme isochronous with the communication cycle or by a communication scheme asynchronous with the communication cycle.
As another embodiment, the invention discloses a program for a data communication process stored in a computer readable storage medium, comprising the steps of: (a) inputting moving image information and still image information; (b) encoding the moving image information and the still image information; and (c) transmitting the moving image to a number of unidentified apparatuses and transmitting the still image information to a designated apparatus.
As another embodiment, the invention discloses a program for a data communication process stored in a computer readable storage medium, comprising the steps of: (a) inputting information data; (b) encoding the information data; and (c) transmitting decode information containing program codes realizing the decoding method corresponding to an encoding method to be used at the encoding step and transmitting the information data encoded at the encoding step.
As another embodiment, the invention discloses a program for a data communication process stored in a computer readable storage medium, comprising the steps of: (a) inputting encoded information data and decode information realizing a decoding process for the information data; and (b) decoding the encoded information data by using the decode information.
As another embodiment, the invention discloses a program for a data communication process stored in a computer readable storage medium, comprising the steps of: (a) encoding information data by using a predetermined encoding scheme; (b) decoding information data encoded at the encoding step; and (c) selecting an output of either the encoded information data or the decoded information data in accordance with whether the encoding scheme corresponds to a decoding scheme at an object node apparatus.
Still other objects of the present invention, and the advantages thereof, will become fully apparent from the following detailed description of the embodiments.